Many serial networks such as the token ring are provided with many ports or access points. In general many of these access points are unoccupied. In addition stations are frequently moved from one access port to another. When failures occur, beacon frames can identify which station may have failed or if a failure exists between two active stations. A technique described in U.S. Pat. No. 4,507,777 (Next Active Upstream Neighbor also known as Neighbor Notification) provides at any point in the network the ability to determine the physical order on the serial network of all upstream stations.
As described in U.S. Pat. No. 5,335,227 it is possible to correlate the sequential addresses of the stations on a network and connected to hub with the active ports thus providing a network topology. U.S. Pat. No. 5,319,633 addresses a special case where more than one station is attached to a single port thus creating a connection ambiguity. The two patents provide a fully adequate technical solution to the problem.
The present invention grew out of an attempt to significantly reduce the cost and complexity of the prior art solution. In the prior art a number of (at least two) very expensive ring adapters are employed to effect the correlation and resolve any ambiguity which would exist in those instances where more than one station is connected to a hub port. Each adapter includes in addition to a variety of integrated circuits a microprocessor. These adapters are in addition to a programmed hub microprocessor with which they communicate.